isaiah 40:3 The voice of him that crieth in the wilderness, Prepare ye the way of the LORD, make straight in the desert a highway for our God. - Free Bible Online

      3. crieth in the wilderness--So the Septuagint and Mt 3:3 connect the words. The Hebrew accents, however, connect them thus: "In the wilderness prepare ye," &c., and the parallelism also requires this, "Prepare ye in the wilderness," answering to "make straight in the desert." Matthew was entitled, as under inspiration, to vary the connection, so as to bring out another sense, included in the Holy Spirit's intention; in Mt 3:1, "John the Baptist, preaching in the wilderness," answers thus to "The voice of one crying in the wilderness." MAURER takes the participle as put for the finite verb (so in Isa 40:6), "A voice crieth." The clause, "in the wilderness," alludes to Israel's passage through it from Egypt to Canaan (Ps 68:7), Jehovah being their leader; so it shall be at the coming restoration of Israel, of which the restoration from Babylon was but a type (not the full realization; for their way from it was not through the "wilderness"). Where John preached (namely, in the wilderness; the type of this earth, a moral wilderness), there were the hearers who are ordered to prepare the way of the Lord, and there was to be the coming of the Lord [BENGEL]. John, though he was immediately followed by the suffering Messiah, is rather the herald of the coming reigning Messiah, as Mal 4:5, 6 ("before the great and dreadful day of the Lord"), proves. Mt 17:11 (compare Ac 3:21) implies that John is not exclusively meant; and that though in one sense Elias has come, in another he is yet to come. John was the figurative Elias, coming "in the spirit and power of Elias" (Lu 1:17); Joh 1:21, where John the Baptist denies that he was the actual Elias, accords with this view. Mal 4:5, 6 cannot have received its exhaustive fulfilment in John; the Jews always understood it of the literal Elijah. As there is another consummating advent of Messiah Himself, so perhaps there is to be of his forerunner Elias, who also was present at the transfiguration.
      the Lord--Hebrew, Jehovah; as this is applied to Jesus, He must be Jehovah (Mt 3:3).

JFB.